Systems and Methods for Determining Properties of Porous, Fluid-Filled Geological Formations Based on Multi-Frequency Measurements

ABSTRACT

Aspects of the present disclosure relate to a method for determining a wettability of one or more types of solid particles within a geological formation. The method may include receiving a plurality of electromagnetic measurements within a frequency range from an electromagnetic well-logging tool. The method may also include determining a contact angle associated with at least one type of solid particles within the geological formation using the electromagnetic measurements.

CROSS-REFERENCE TO RELATED APPLICATION

The present document is based on and claims priority to U.S. Provisional Application Ser. No. 62/879,882, filed Jul. 29, 2019, which is incorporated herein by reference in its entirety.

BACKGROUND

This disclosure relates to determining properties of porous, fluid-fluid geological formations based on multi-frequency electromagnetic measurements.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

Producing hydrocarbons from a wellbore drilled into a geological formation is a remarkably complex endeavor. In many cases, decisions involved in hydrocarbon exploration and production may be informed by measurements from downhole well-logging tools that are conveyed deep into the wellbore. The measurements may be used to infer properties and characteristics of the geological formation surrounding the wellbore. The discovery and observation of resources using downhole techniques generally takes place down in the wellbore with certain sensors. Electromagnetic well-logging sensors or induction well-logging sensors use electromagnetic waves to acquire measurements, which may inform the decisions involved in hydrocarbon exploration and production. The composition of the geological formation may increase the complexity of the measurements by adding artifacts.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

One embodiment of the present disclosure relates to a method for determining a wettability of one or more types of solid particles within a geological formation. The method includes receiving a plurality of electromagnetic (EM) measurements within a defined frequency range from an electromagnetic well-logging tool. The method also includes determining a contact angle associated with at least one type of solid particle within the geological formation based on the received plurality of EM measurements.

Another embodiment of the present disclosure relates to an article of manufacturer comprising instructions that, when executed by at least one processor, cause the at least one processor to receive one or more inputs indicative of properties of a geological formation as inputs to a mechanistic model, wherein the mechanistic model correlates one or more fluid phases, compositions, or both, to a contact angle of at least one type of solid particle associated with the geological formation and correlates an interfacial polarization of the at least one type of solid particles to the contact angle of the at least one type of solid particle. The instructions also cause the at least one processor to generate, as an output by the mechanistic model, a set of frequencies to measure by a downhole tool, wherein the set of frequencies corresponds to where frequency dispersions in conductivity, permittivity, or both are measureable.

Another embodiment of the present disclosure relates to a system for determining physical properties of a porous, fluid-filled geological formation. The system includes a data processing system that has a processor and a memory storing instructions that, when executed by the processor, cause the processor to receive, as an input to a mechanistic model, one or more inputs indicative of estimated properties of the porous, fluid-filled geological formation, wherein the mechanistic model correlates one or more fluid phases, compositions, or both, to a contact angle of at least one type of solid particle and correlates an interfacial polarization of the at least one type of solid particle to the contact angle of the ay least one type of solid particle. The instructions also cause the at least one processor to generate, as an output by the mechanistic model, a set of frequencies to measure by a downhole tool, wherein the set of frequencies corresponds to where frequency dispersions in conductivity, permittivity, or both are measureable. The system also includes the electromagnetic well-logging tool configured to tune an electromagnetic (EM) measurement based on the set of frequencies and acquire measurements based on the set of frequencies.

Various refinements of the features noted above may be undertaken in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 is an example of a neutron-induced gamma-ray spectroscopy system, in accordance with an embodiment;

FIG. 2 is an example of a neutron-induced gamma-ray spectroscopy downhole tool, in accordance with an embodiment;

FIG. 3 is an example of a process for determining properties of a fluid-filled formation, in accordance with an embodiment;

FIG. 4 is an example illustration of a cross section of a volume that includes a solid suspended in an oil-water media, in accordance with an embodiment;

FIG. 5A shows a graph illustrating an example of determined effective conductivity for fluid-filled porous material for different contact angles with a 10% oil saturation, in accordance with an embodiment;

FIG. 5B shows a graph illustrating an example of determined effective conductivity for fluid-filled porous material for different contact angles with a 90% oil saturation, in accordance with an embodiment;

FIG. 5C shows a graph illustrating an example of determined effective permittivity for fluid-filled porous material for different contact angles with a 10% oil saturation, in accordance with an embodiment;

FIG. 5D shows a graph illustrating an example of determined effective permittivity for fluid-filled porous material for different contact angles with a 90% oil saturation, in accordance with an embodiment;

FIG. 6A shows a graph illustrating an example of determined effective conductivity for fluid-filled porous material for different oil saturations with a contact angle of 30°, in accordance with an embodiment;

FIG. 6B shows a graph illustrating an example of determined effective conductivity for fluid-filled porous material for different oil saturations with a contact angle of 90°, in accordance with an embodiment;

FIG. 6C shows a graph illustrating an example of determined effective conductivity for fluid-filled porous material for different oil saturations with a contact angle of 150°, in accordance with an embodiment;

FIG. 6D shows a graph illustrating an example of determined effective permittivity for fluid-filled porous material for different oil saturations with a contact angle of 30°, in accordance with an embodiment;

FIG. 6E shows a graph illustrating an example of determined effective permittivity for fluid-filled porous material for different oil saturations with a contact angle of 90°, in accordance with an embodiment;

FIG. 6F shows a graph illustrating an example of determined effective permittivity for fluid-filled porous material for different oil saturations with a contact angle of 150°, in accordance with an embodiment;

FIG. 7A shows graphs depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates of clay surface conductance for oil-water-filled porous material containing water-wet sands, clays, and graphite, in accordance with an embodiment;

FIG. 7B shows graphs depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates of graphite contact angle for oil-water-filled porous material containing water-wet sands, clays, and graphite, in accordance with an embodiment;

FIG. 7C shows graphs depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates of water conductivity for oil-water-filled porous material containing water-wet sands, clays, and graphite, in accordance with an embodiment;

FIG. 8A shows graphs depicting a histogram of MCMC inversion-derived estimates of clay surface conductance of FIG. 7A, in accordance with an embodiment;

FIG. 8B shows graphs depicting a histogram of MCMC inversion-derived estimates of graphite contact angle of FIG. 7B, in accordance with an embodiment;

FIG. 8C shows graphs depicting a histogram of MCMC inversion-derived estimates of water conductivity of FIG. 7C, in accordance with an embodiment;

FIG. 9A shows multi-frequency electromagnetic (EM) measurements and model predictions based on inversion-derived estimates of effective conductivity associated with FIGS. 7A, 7B, and 7C and FIGS. 8A, 8B, and 8C, in accordance with an embodiment;

FIG. 9B shows multi-frequency electromagnetic (EM) measurements and model predictions based on inversion-derived estimates of effective permittivity associated with FIGS. 7A, 7B, and 7C and FIGS. 8A, 8B, and 8C, in accordance with an embodiment;

FIG. 10A shows graphs depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates for clay surface conductance for oil-water-filled porous material containing water-wet sands, clays, and slightly oil-wet graphite, in accordance with an embodiment;

FIG. 10B shows graphs depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates for graphite contact angle for oil-water-filled porous material containing water-wet sands, clays, and slightly oil-wet graphite, in accordance with an embodiment;

FIG. 10C shows graphs depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates for water conductivity for oil-water-filled porous material containing water-wet sands, clays, and slightly oil-wet graphite, in accordance with an embodiment;

FIG. 11A shows graphs depicting a histogram of MCMC inversion-derived estimates of clay surface conductance of FIG. 10A, in accordance with an embodiment;

FIG. 11B shows graphs depicting a histogram of MCMC inversion-derived estimates of graphite contact angle of FIG. 10B, in accordance with an embodiment;

FIG. 11C shows graphs depicting a histogram of MCMC inversion-derived estimates of water conductivity of FIG. 10C, in accordance with an embodiment;

FIG. 12A shows multi-frequency EM measurements and model predictions for effective conductivity based on inversion-derived estimates associated with FIGS. 10A, 10B, and 10C and FIGS. 11A, 11B, and 11C, in accordance with an embodiment;

FIG. 12B shows multi-frequency EM measurements and model predictions for effective permittivity based on inversion-derived estimates associated with FIGS. 10A, 10B, and 10C and FIGS. 11A, 11B, and 11C, in accordance with an embodiment;

FIG. 13A shows a graph depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates for contact angle for oil/water-filled porous material containing water-wet sand and clays and oil-wet graphite, in accordance with an embodiment;

FIG. 13B shows a graph depicting a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates for contact angle for oil saturation oil/water-filled porous material containing water-wet sand and clays and oil-wet graphite, in accordance with an embodiment;

FIG. 14A shows a graph depicting a histogram of MCMC inversion-derived estimates of clay surface conductance of FIG. 13A, in accordance with an embodiment;

FIG. 14B shows a graph depicting a histogram of MCMC inversion-derived estimates of oil saturation of FIG. 13B, in accordance with an embodiment;

FIG. 15A shows multi-frequency EM measurements and model predictions for effective conductance based on inversion-derived estimates associated with FIGS. 13A and 13B, and FIGS. 14A and 14B, in accordance with an embodiment; and

FIG. 15B shows multi-frequency EM measurements and model predictions for effective permittivity based on inversion-derived estimates associated with FIGS. 13A and 13B, and FIGS. 14A and 14B, in accordance with an embodiment.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

As used herein, “wettability” refers to a tendency of one fluid to spread on and/or adhere to a solid surface in the presence of other immiscible fluids. “Wettability” may be quantified by a contact angle where a liquid interface meets a solid surface.

As discussed above, electromagnetic well-logging or induction well-logging may inform certain decisions related to hydrocarbon exploration and production. Certain existing techniques in electromagnetic well logging may use models that assume that conductive particles, like graphite and pyrite, and surface-charge-bearing non-conductive particles, like quartz, calcite and clays, are completely water wet (e.g., the contact angle between a liquid and a solid surface is zero). It is presently noted that wettability of conductive particles and surface-charge-bearing non-conductive particles governs the preferential spreading of fluids on the surface of the particles that influences the interfacial polarization phenomena and charge transport/accumulation around the particles. Consequently, wettability of conductive particles influences the electromagnetic properties of fluid-filled porous materials. Further, the wettability and the electrical properties are closely related such that wettability can be estimated using the electromagnetic properties. For example, the dielectric permittivity of oil-wet sand is smaller than that of the water-wet sand at low water saturation, while the dielectric permittivity of oil-wet sand becomes much larger than that of the water-wet sand at higher water saturation. Additionally, it is noted that both resistivity and magnitude of the phase increase with the increase of oil saturation for sand saturated with non-wetting oil, while they both decrease with the increase of oil saturation for sand partially saturated with wetting oil.

Accordingly, one aspect of the present disclosure relates to systems and methods for using a material and subsurface characterization model to quantify the effects of wettability of conductive. Moreover, the model may be implemented to determine the wettability effects of solid particles that produce interfacial polarization phenomena on multi-frequency electromagnetic measurements. Further, the material and subsurface characterization model, in accordance with the present disclosure, provides a novel technique for identifying a range of operating frequencies for electromagnetic measurements to characterize the contact angle of solid particles that are present within a subsurface formation.

With this in mind, FIG. 1 illustrates an electromagnetic well-logging system 10 that may employ the systems and methods of this disclosure. The electromagnetic well-logging system 10 may be used to convey an electromagnetic well-logging tool 12 through a geological formation 14 via a wellbore 16. The electromagnetic well-logging tool 12 may be conveyed on a cable 18 via a logging winch system 20. Although the logging winch system 20 is schematically shown in FIG. 1 as a mobile logging winch system carried by a truck, the logging winch system 20 may be substantially fixed (e.g., a long-term installation that is substantially permanent or modular). Any suitable cable 18 for well logging may be used. The cable 18 may be spooled and unspooled on a drum 22 and an auxiliary power source 24 may provide energy to the logging winch system 20 and/or the electromagnetic well-logging tool 12.

Moreover, although the electromagnetic well-logging tool 12 is described as a wireline downhole tool, it should be appreciated that any suitable conveyance may be used. For example, the electromagnetic well-logging tool 12 may instead be conveyed as a logging-while-drilling (LWD) tool as part of a bottom hole assembly (BHA) of a drill string, conveyed on a slickline or via coiled tubing, and so forth. For the purposes of this disclosure, the electromagnetic well-logging tool 12 may be any suitable measurement tool that obtains electromagnetic logging measurements through depths of the wellbore 16.

Many types of electromagnetic well-logging tools 12 may obtain electromagnetic logging measurements in the wellbore 16. These include, for example, the Rt Scanner, AIT, and Thrubit Electromagnetic tools by Schlumberger Technology Corporation, but electromagnetic logging measurements from other downhole tools by other manufacturers may also be used. The electromagnetic well-logging tool 12 may provide electromagnetic logging measurements 26 to a data processing system 28 via any suitable telemetry (e.g., via electrical signals pulsed through the geological formation 14 or via mud pulse telemetry). The data processing system 28 may process the electromagnetic logging measurements 26 to identify a contact angel and/or wettability at various depths of the geological formation 14 in the wellbore 16.

To this end, the data processing system 28 thus may be any electronic data processing system that can be used to carry out the systems and methods of this disclosure. For example, the data processing system 28 may include a processor 30, which may execute instructions stored in memory 32 and/or storage 34. As such, the memory 32 and/or the storage 34 of the data processing system 28 may be any suitable article of manufacture that can store the instructions. The memory 32 and/or the storage 34 may be ROM memory, random-access memory (RAM), flash memory, an optical storage medium, or a hard disk drive, to name a few examples. A display 36, which may be any suitable electronic display, may provide a visualization, a well log, or other indication of properties in the geological formation 14 or the wellbore 16 using the electromagnetic logging measurements 26.

FIG. 2 shows an example of an electromagnetic well-logging tool 12 that may acquire electromagnetic measurements. The illustrated embodiment of the electromagnetic well-logging tool 12 includes a transmitter 40 and a receiver 42. While only one transmitter 40 and one receiver 42 are shown, it should be noted that the number of transmitters and receivers is not a limit on the scope of the present disclosure. Generally speaking, the transmitter 40 induces electric eddy currents to produce electromagnetic waves 44 having a set of frequencies in a direction of the magnetic dipole moment of the transmitter 40. The electromagnetic waves 44 that interact with the geological formation 14 are subsequently received by the receiver 42 to generate electromagnetic measurements.

As shown in FIG. 2, the illustrated embodiment of the electromagnetic well-logging tool 12 is communicatively coupled to the data processing system 28, which includes a material and subsurface characterization model 46 stored in the memory 32. As discussed in further detail below, the material and subsurface characterization model 46 may be utilized by the processor 30 of the data processing system 28 to determine a set of frequencies that the electromagnetic well-logging tool 12 may operate to acquire electromagnetic measurements. Further, the electromagnetic measurements may be processed according to the present disclosure to quantify the wettability effects of graphite, clays and other conductive or surface-charge-bearing non-conductive particles for improving subsurface electromagnetic log measurement interpretation in various subsurface geological formations to better quantify the water content/saturation in the subsurface.

FIG. 3 illustrates a process 50 for determining one or more physical properties of a fluid-filled geological formation. Although described in a particular order, which represents a particular embodiment, it should be noted that the process 50 may be performed in any suitable order. Additionally, embodiments of the process 50 may omit process blocks and/or include additional process blocks. Moreover, in some embodiments, the process 50 may be implemented at least in part by executing instructions stored in a tangible, non-transitory, computer-readable medium, such as memory 32 implemented in a data processing system 28, using processing circuitry, such as a processor 30 implemented in the data processing system 28.

In general, the illustrated process 50 includes receiving (process block 52) electromagnetic measurements from a set of frequencies (e.g., emitted by the electromagnetic well-logging tool 12), and determining (process block 54) one or more physical properties of the geological formation.

As described herein, in some embodiments, the set of frequencies emitted by the electromagnetic well-logging tool 12 may be determined based on the material and subsurface characterization model 46. For example, an operator may determine a number (e.g., 1, 2, 3, 4, 5 etc.) properties of a fluid-filled porous material to be estimated (e.g., determined) and provide these at inputs to a suitable computing system (e.g., the data processing system 28). In some embodiments, the properties to be estimated may include contact angle of conductive particles, contact angle of surface-charge-bearing particles, fluid saturations, fluid conductivity/salinity, surface conductance of particles, diffusion coefficients of charge carriers in various components of the material, and volume fractions of fluid and solid components in the materials. Further, the operator may provide an initial assumption of the composition of the geological formation, and the properties of the fluid and solid components in the geological formation. Based on the initial assumption, the operator may apply the material and subsurface characterization model 46 to identify the set of frequencies where frequency dispersions in conductivity and/or permittivity will be dominant and measureable (e.g., absent certain effects related to the complex conductivity and/or complex permittivity as described herein). In some embodiments, the set of frequencies may be a range of frequencies or one or more discrete frequencies.

The identified frequency range may be provided as an output to the electromagnetic well-logging tool 12. For example, the data processing system 28 may provide an output that instructs the electromagnetic well-logging tool 12 to tune the electromagnetic (EM) measurement to measure multi-frequency complex conductivity/permittivity of the fluid-filled porous material within the identified frequency ranges, or at specific frequencies in the frequency range. In some embodiments, the number of discrete frequencies included in the identified frequency range or the number of specific frequencies may be at least 3 times the number of physical properties to be estimated as described above.

As such, the electromagnetic well-logging tool 12 may perform the electromagnetic (EM) measurements of multi-frequency complex conductivity/permittivity on the fluid-filled porous material using the measurement settings tuned and finalized in the steps as described above. In some embodiments, a Markov-Chain Monte-Carlo may be applied to the EM measurements received in process block 52 to determine properties such as the contact angles and other physical properties as described herein.

The material and subsurface characterization model 46 may include multiple relationships, or be generated based on multiple models. For example, the material and subsurface characterization model 46 may include a first mechanistic model for a solid particle being preferentially surrounded by one of the fluid phases or fluid components surrounding the solid particle as a function of the contact angle of the solid particle. Further, the material and subsurface characterization model 46 may include a second mechanistic model that quantifies the interfacial polarization due to a solid particle (conductive or surface-charge-bearing non-conductive particle) preferentially surrounded by one of the fluid phases/components surrounding the solid particle as function of the contact angle of the solid particle and the operating frequency of the externally applied electromagnetic field.

The material and subsurface characterization model 46 may be developed by solving the Young-Laplace equation for a spherical grain in a mixture of wetting and non-wetting fluids with a known proportion of the two fluids. For example, Young-Laplace equation may be used to compute the shape of the wetting and non-wetting fluid interface (meniscus) at equilibrium by applying appropriate boundary conditions. In this way, the following expressions may be obtained: the wetting angle of the conductive or surface-charge-bearing non-conductive particle as a function of contact angle of the solid particle and the properties of fluid phases/components surrounding the solid particle. It should be noted that the interfacial polarization due to conductive and surface-charge-bearing non-conductive solid particles depends on the nature of preferential wetting of the solid particle. As such, the materials subsurface characterization model 46 may be used to quantify the effects of contact angle (wettability) of solid grains/particles (conductive or surface-charge-bearing non-conductive particle) on the net charge transport and net charge accumulation as a function of the frequency of the external electromagnetic field at various fluid saturations and solid wettability. The net charge transport determines the conductivity and net charge accumulation determines the permittivity that govern the electromagnetic measurements and log responses of the fluid-filled porous material.

At the representative volume level, developing the material and subsurface characterization model 46, in accordance with the techniques of the present disclosure, may include assuming the non-wetting layer (e.g., oil) stays at the top, wetting layer (e.g., water) goes to the bottom, the two layers have (e.g., the non-wetting layer and the wetting layer) one common interface, and the two layers are spread across a length scale that is orders of magnitude larger than the size of the spherical solid particle. The height of these two layers are in proportion to the corresponding fluid saturations. The solid particle suspends at the interface of wetting and non-wetting fluids, as shown in the FIG. 4, is discussed below. The wetting phase may surround the solid particle to satisfy the contact angle. The climb or height of the interface between the wetting layer and the non-wetting layer generates a wetting angle, which represents the degree of exposure of the particle to the wetting phase. The interfacial polarization phenomena due to such solid particles are entirely governed by the extent to which the solid particle is surround by the wetting phase versus non-wetting phase, which is governed by the wettability and contact angle of the solid particle. For example, when water wets a conductive mineral, its interfacial polarization effects on the complex conductivity/permittivity measurements will be enhanced. In another example, when the conductive mineral is preferentially oil wet, its interfacial polarization effects on the complex conductivity/permittivity measurements will diminish.

FIG. 4 is an example illustration of a cross-section of a volume 56 (e.g., within a geological formation) that includes a solid particle 57 suspended in an oil-water media, in accordance with an embodiment. In general, the volume 56 may be assumed for developing the model, as discussed herein. As shown, the solid particle 57 is a circle (e.g., a cross-section of a sphere); however, it should be noted that, in some embodiments, the solid particle may be ellipsoidal (e.g., a diameter 58 of the solid particle 57 may be greater than or less than a diameter 59 of the solid particle 57) or have a radial normal distribution of radii.

In the illustrated cross-section of the volume 56 shown in FIG. 4, C denotes the point where the oil-water interface (e.g., interface between the non-wetting layer and the wetting layer) contacts the particle surface; θ is the contact angle of conductive particle; φ is the wetting angle; ψ is the angle between oil-water interface and the horizon (x-axis) at point C; R is the radius of conductive particle; h_(i) is the uniform height of oil-water interface in the absence of wetting of the conductive particle (far-field height); h_(c) is the height where the oil-water interface contacts the particle surface, such that h_(c)=R(1−cos φ); r is the horizontal distance perpendicular to the vertical axis z; and h(r) is the height of oil-water interface at any distance r away from the vertical axis z.

Young-Laplace Equation

As discussed herein, developing the material and subsurface characterization model 46 may include solving the Young-Laplace equation to quantify the shape of the oil-water interface. For example, the shape of the oil-water interface, where oil is non-wetting phase and water is the wetting phase, at equilibrium may be described by the Young-Laplace equation:

(ρ_(w)−ρ_(o))g[h(r)−h _(i)]=2Hσ

where ρ_(w) and ρ_(o) are the density of water and oil, respectively; g denotes gravitational acceleration; H is mean curvature of the meniscus surface; and σ is interfacial tension between oil and water.

Under a small slope assumption, where the Bond number,

${B_{0} = \frac{\left( {\rho_{w} - \rho_{o}} \right)gR^{2}}{\sigma}},$

is small, the gravity force is negligible, so the mean curvature may remain constant everywhere on the oil-water interface. For the material and subsurface characterization model 46, the meniscus surface is axisymmetric. As a result, the Young-Laplace equation can be expressed in cylindrical coordinates as:

$\frac{\left( {\rho_{w} - \rho_{o}} \right){g\left\lbrack {{h(r)} - h_{i}} \right\rbrack}}{\sigma} = {h^{''} + \frac{h^{\prime}}{r}}$

where h′ and h″ represents

${\frac{dh}{dr}\mspace{14mu} {and}\mspace{14mu} \frac{d^{2}h}{{dr}^{2}}},$

respectively.

By defining some dimensionless variables, such as

${\hat{r} = \frac{r}{L_{c}}},{\hat{h} = \frac{h}{L_{c}}},{{G\left( \hat{r} \right)} = \frac{{h(r)} - h_{i}}{L_{c}}},$

where

$L_{c} = \sqrt{\frac{\sigma}{\left( {\rho_{w} - \rho_{o}} \right)g}}$

is capillary length, the Young-Laplace equation becomes a modified Bessel differential equation:

${G^{''} + \frac{G^{\prime}}{\hat{r}} - G} = 0$

where G′ and G″ represents

${\frac{dG}{d\hat{r}}\mspace{14mu} {and}\mspace{14mu} \frac{d^{2}G}{d{\hat{r}}^{2}}},$

respectively.

Boundary Conditions (BC)

As discussed herein, developing the material and subsurface characterization model 46 may include solving the Young-Laplace equation with certain boundary conditions. For example, a first boundary condition may be the height of oil-water interface at infinite distance, h(r)|_(r→∞), is equal to h_(i).

${\lim\limits_{\hat{r}\rightarrow\infty}G} = 0$ (lim)_(⊥)(r{circumflex over ( )}→∞)G=0

A secondary boundary condition may be the height of oil-water interface at distance r=R sin φ is h_(c).

G({circumflex over (r)}=√{square root over (B _(o))} sin φ)=ĥ _(c) −ĥ _(i)

Shape of the Oil-Water Interface

The Young-Laplace equation is solved using the boundary conditions to obtain the expression for the shape of the oil-water interface:

$\hat{h} = {{\hat{h}}_{i} + {\frac{{\hat{h}}_{c} - {\hat{h}}_{i}}{K_{0}\left( {\sqrt{B_{o}}\sin \; \phi} \right)}{K_{0}\left( \hat{r} \right)}}}$

where K_0 is modified Bessel function of the second kind of order 0.

An Expression of Wetting Angle

Wetting angle may be expressed as:

$\phi = {180 - \theta - {\frac{{\hat{h}}_{c} - {\hat{h}}_{i}}{K_{0}\left( {\sqrt{B_{o}}\sin \; \varphi} \right)}{K_{1}\left( {\sqrt{B_{o}}\sin \; \phi} \right)}}}$

where K_1 is modified Bessel function of the second kind of order 1.

Effective Medium Model

In some embodiments, developing the material and subsurface characterization model 46 may include using an effective medium model. For example, to simulate the wettability effects of solid particles constituting a fluid-filled porous material on the electromagnetic properties of the material (e.g., multi-frequency complex conductivity and complex permittivity), the newly developed model of wetting angle of a solid particle may include a petrophysical model to express the complex conductivity/permittivity due to the interfacial polarization of the solid particles at various saturations, wettability, and operating frequencies.

From an effective medium standpoint, the effective complex conductivity of a porous fluid-filled geomaterial containing conductive particles of any wettability (e.g., graphite particle) and fully wetted surface-charge-bearing non-conductive particles (e.g., water-wet sand and clay particles) at any saturation of the wetting phase (e.g., water) may be expressed as:

$\frac{K_{eff} - K_{w}}{K_{eff} + {2K_{w}}} = {{\varphi_{c}p_{w}{f_{c,w}(\omega)}} + {{\varphi_{c}\left( {1 - p_{w}} \right)}{f_{c,{nw}}(\omega)}} + {\varphi_{n1}{f_{n1}(\omega)}} + {\varphi_{n2}{f_{n2}(\omega)}} + {\varphi_{nw}{f_{nw}(\omega)}}}$

Where K_(eff) is the effective complex conductivity of the porous fluid-filled geomaterial; K_(w) is the complex conductivity of pore-filling wetting phase, which may be brine or saline water in some cases, with an assumption that the complex conductivity of pore-filling non-wetting phase, which is oil in in the illustration of the cross-section of the volume 56, is negligible; f is the dipolarizability due to interfacial polarization of solid particle; ω is the angular frequency of the external EM field; ϕ is the volume fraction of solid particles or the fluid phases; p_(w) is the proportion of a single solid particle surface that is covered by wetting phase (water) determined using the newly developed model of wetting angle of a solid particle; and subscripts c, n1, n2, nw, and w represent the conductive particle of any wettability (e.g., graphite), water-wet surface-charge-bearing non-conductive particle #1 (e.g., sand), water-wet surface-charge-bearing non-conductive particle #2 (e.g., clay), non-wetting phase (e.g., oil), and wetting phase (e.g., water), respectively.

When a solid particle is not fully wet, the interfacial polarization effect of such a solid particle is determined as a volumetric mixing of interfacial polarization when the solid particle is completely surrounded by non-wetting fluid phase, f_(c,nw), and that when completely surround by wetting fluid phase, f_(c,w), expressed as pp_(w)f_(c,w)(ω)+ϕ_(c)(1−p_(w))f_(c,nw)(ω), where p_(w) is the proportion of the solid particle surface that is covered by wetting phase (water) determined using the newly developed model of wetting angle of a solid particle.

The proportion of a single graphite surface that covered by water or oil may be expressed as:

$p_{w} = \frac{1 - {\cos \; \phi}}{2}$

where φ is the wetting angle.

Dipolarizability of conductive particle (e.g., graphite) completely immersed in wetting phase may be expressed as:

${f_{c}(\omega)} = {{- \frac{1}{2}} + {\frac{3}{2}\frac{i\omega}{\left\lbrack {{\frac{2}{a}\frac{\sigma_{w}}{ɛ_{w}}\frac{E_{w}}{G_{w}}} - {\frac{2}{a}\frac{K_{w}}{K_{c}}\frac{\sigma_{c}}{ɛ_{c}}\frac{F_{c}}{H_{c}}} + {i{\omega \left( {\frac{2K_{w}}{K_{c}} + 1} \right)}}} \right\rbrack}}}$ where: $E_{w} = {\frac{q}{\gamma_{w}^{2}ɛ_{w}}{e^{{- a}\gamma_{w}}\left\lbrack {\frac{1}{a\gamma_{w}} + \frac{1}{\left( {a\gamma_{w}} \right)^{2}}} \right\rbrack}}$ $G_{w} = {\frac{q}{\gamma_{w}ɛ_{w}}{e^{{- a}\gamma_{w}}\left\lbrack {\frac{1}{a\gamma_{w}} + \frac{2}{\left( {a\gamma_{w}} \right)^{2}} + \frac{2}{\left( {a\gamma_{w}} \right)^{3}}} \right\rbrack}}$ $F_{c} = {\frac{q}{\gamma_{c}^{2}ɛ_{c}}\left\lbrack {\frac{\cosh \left( {a\gamma_{c}} \right)}{a\gamma_{c}} - \frac{\sinh \left( {a\gamma_{c}} \right)}{\left( {a\gamma_{c}} \right)^{2}}} \right\rbrack}$ $H_{c} = {\frac{q}{\gamma_{c}ɛ_{c}}\left\lbrack {\frac{2{\cosh \left( {a\gamma_{c}} \right)}}{\left( {a\gamma_{c}} \right)^{2}} - \frac{\sinh \left( {a\gamma_{c}} \right)}{a\gamma_{c}} - \frac{2{\sinh \left( {a\gamma_{c}} \right)}}{\left( {a\gamma_{c}} \right)^{3}}} \right\rbrack}$ ${\gamma_{j} = \sqrt{\frac{i\omega}{D_{j}} + \frac{\sigma_{j}}{ɛ_{j}D_{j}}}},{{{for}\mspace{14mu} j} = {w\mspace{14mu} {or}\mspace{14mu} c}}$

where ω is the angular frequency of the electric field; i is square root of −1; a is characteristic length of inclusion phase; λ is surface conductance of nonconductive particle; σ is electrical conductivity; ε is dielectric permittivity; and D is diffusion coefficient of charge carriers.

Dipolarizability of nonconductive particle (e.g., clay, sand, oil) completely immersed in wetting phase may be expressed as:

${f_{ncond}(\omega)} = \frac{{Q\left( {R + A} \right)} - P}{{Q\left( {R - {2A}} \right)} + {2P}}$ where: $A = \frac{1}{a^{2}}$ ${P = {{\gamma_{w}^{2} + {\xi_{w}^{2}\frac{G^{*}}{H^{*}}} + {\frac{2G^{*}}{a^{2}L}Q}} = {{{\frac{1}{{iF} + 1}\left\lbrack {2 - {\frac{a^{2}\xi_{h}^{2}}{H^{*}}\left( {\frac{L}{iF} + E} \right)} - \frac{2E}{L}} \right\rbrack}R} = {{\frac{P}{Q}\left( \frac{{iFE} + L}{{iF} + 1} \right)H^{*}} = \frac{aL_{w}}{F_{w}}}}}},{G^{*} = \frac{aG_{w}}{E_{w}}},{L = \frac{2\lambda}{a\sigma_{w}}},{E = \frac{ɛ_{n}}{ɛ_{w}}},{F = \frac{\omega ɛ_{w}}{\sigma_{w}}}$ $F_{w} = {{\frac{q}{\xi_{w}^{2}ɛ_{w}}{e^{{- a}\xi_{w}}\left\lbrack {\frac{1}{a\; \xi_{w}} + \frac{1}{\left( {a\; \xi_{w}} \right)^{2}}} \right\rbrack}L_{w}} = {\frac{q}{\zeta_{w}ɛ_{w}}{e^{{- a}\xi_{w}}\left\lbrack {\frac{1}{a\; \xi_{w}} + \frac{2}{\left( {a\; \xi_{w}} \right)^{2}} + \frac{2}{\left( {a\; \xi_{w}} \right)^{3}}} \right\rbrack}}}$ ${\xi_{j} = \sqrt{\frac{i\omega}{D_{j}}}},{{{for}\mspace{14mu} j} = {n\mspace{14mu} {or}\mspace{14mu} w}}$

Based on certain assumptions of the properties of solid particles and fluid phases in the fluid-filled porous material and the list of unknown properties to be estimated, the new mechanistic model is used to identify the frequency range where frequency dispersions in conductivity and/or permittivity will be dominant and measurable for purposes of desired estimations. Electromagnetic (EM) measurements in all the following cases (presented in FIGS. 4 to 7) were tuned to be within the frequency range identified using the mechanistic model, such that the number of discrete frequencies as which the measurements were acquired is at least 3 times the number of physical properties to be estimated. The following case demonstrates the use of mechanistic model to plan the electromagnetic (EM) data acquisition procedure.

TABLE 1 Example properties of wetting phase D_(w) (m²/s) ε_(r, w) σ_(w) (S/m) ρ_(w) (kg/m³) σ (N/m) Water 10⁻⁹ 70 0.1 1000 0.05

TABLE 2 Example properties of solid particles, i is c for conductive particle (e.g., graphite), i is n for surface-charge-bearing non-conductive particle (e.g., clay and sand), and i is nw for non-wetting phase (e.g., oil). ϕ_(i) (%) a_(i) (μm) D_(i) (m²/s) ε_(r, i) σ_(i) (S/m) λ (S) θ (°) Graphite 10 200 5 × 10⁻⁵ 12 500 — 0~180 Sand 70 1000 — 4 — 10⁻⁹ — Clay 10 100 — 8 — 10⁻⁸ — Oil 1~9 100 — 2 —  10⁻³⁰ —

FIGS. 5A and 5B show graphs of effective conductivity and FIGS. 5C and 5D show graphs of effective permittivity for mixtures including a conductive solid particle. More specifically, the curves in the graph 62 and graph 64 show effective conductivity, and the curves in the graph 66 and graph 68 show effective permittivity. When comparing the different curves in graph 62 and graph 66, or graph 64 and graph 68, the frequency dispersion reduces as contact angle increases, which means the conductive particle becomes oil wet. This is because, as contact angle increases, the graphite surface is covered more by oil, which has much fewer charge carriers than water and impedes the interfacial polarization in the fluid phase which lowers charge accumulation. As oil saturation increases, both σ_eff and ε_(r,eff) will reduce due to the increase in the volume fraction of oil as nonconductive inclusion. Both σ_eff and ε_(r,eff) will converge to a single value at high frequency because the charge carriers rapidly respond to the alternating external EM field and there is no net accumulation around particles, resulting in an apparent increase in conductivity. Consequently, conductivity reaches to a high value and permittivity reaches to a low value (representing only dipole moment of water) at high frequency close to 1 GHz. In the contrast, at low frequency, the charge carriers quickly reach the equilibrium distribution around the conductive particles' interface, so that the polarized particles act as insulators, which lead to lower σ_eff and higher ε_(r,eff). σ_eff at low frequency can be modeled using effective medium model assuming the conductive particles to be insulators.

FIGS. 6A, 6B, and 6C (i.e., FIGS. 6A-C) show graphs of effective conductivity and FIGS. 6D, 6E, and 6F (i.e., FIGS. 6D-F) effective permittivity for mixtures including a conductive solid particle. More specifically, the curves in the graph 70, graph 72, and graph 74 show effective conductivity, and the curves in the graph 76, graph 78, and graph 80 show effective permittivity. When comparing the different curves in graph 70 and graph 76, graph 72 and graph 78, and graph 74 and graph 80, the frequency dispersion reduces as oil saturation increases because graphite surface is covered more by oil, similar to the effect of contact angle. It should be noted that as oil saturation increases, both σ_eff and ε_(r,eff) will reduce due to the increase in the volume fraction of oil because the oil behaves as nonconductive inclusion. Also, by comparing the rate of change among curves in graph 62 and graph 66 (e.g., as shown in FIGS. 5A and 5C) and graph 70 and graph 76 (e.g., as shown in FIGS. 6A and 6D), it is evident that the effect of change in oil saturation from 10% to 70% on the frequency dispersion of conductivity and permittivity is much lower than the effect of change in contact angle from 0° to 180°. This indicates that the contact angle plays a primary effect and oil saturation plays a secondary effect in controlling the multi-frequency behavior.

The following three cases demonstrate the efficacy of the electromagnetic (EM) data acquisition procedure followed by data processing workflow. Based on some assumption of the properties of solid particles and fluid phases in the fluid-filled porous material and the list of unknown properties to be estimated, the new mechanistic model is used to identify the frequency range where frequency dispersions in conductivity and/or permittivity will be dominant and measurable for purposes of desired estimations. Electromagnetic (EM) measurements in all the following cases (presented in FIGS. 5A, 5B, 5C, and 5D, FIGS. 6A-C, FIGS. 6D-F, and FIGS. 7A, 7B, and 7C) were tuned to be within the frequency range identified using the mechanistic model, such that the number of discrete frequencies at which the measurements were acquired is at least 3 times the number of physical properties to be estimated. Using the MCMC inversion coupled with the mechanistic model, several properties of the fluid-filled porous materials were estimated, the primary being the simultaneous estimations of oil saturation (or water saturation) and contact angle (or wettability).

FIGS. 7A, 7B, and 7C (i.e., FIGS. 7A-C) show a graph 90, a graph 92, and a graph 94, which each depict a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates. More specifically, the graph 90, the graph 92, and the graph 94 illustrate the MCMC inversion of multi-frequency EM measurements of conductivity and permittivity (shown in FIG. 5.3) to estimate clay surface conductance λ_(c) (e.g., shown in graph 90), graphite contact angle θ (e.g., shown in graph 92), and water conductivity σ_(w) (e.g., shown in graph 90) for oil/water-filled porous material containing water-wet sand, clays, and graphite.

FIGS. 8A, 8B, and 8C (i.e., FIGS. 8A-C) show a graph 96, a graph 98, and a graph 100, which each depict a histogram of MCMC inversion-derived estimates of clay surface conductance, graphite contact angle, and water conductivity. The graph 96, the graph 98, and the graph 100 represent histograms of MCMC inversion-derived estimates of clay surface conductance λ_(c) (e.g., shown in graph 96), graphite contact angle θ (e.g., shown in graph 98), and water conductivity σ_(w) (e.g., shown in graph 100). A line 102 represents the original values of the properties and the region between lines 104 and 106 represent 90% highest posterior density (HPD) interval of the inversion-derived estimates.

FIGS. 9A and 9B show a graph 108 of multi-frequency EM measurements and a graph 110 of model predictions based on inversion-derived estimates. More specifically, the graph 108 and the graph 110 illustrates a comparison of the multi-frequency EM measurements against the mechanistic model predictions for effective permittivity based on the inversion-derived estimates for effective conductance and effective permittivity.

FIGS. 10A, 10B, and 10C show a graph 112, a graph 114, and a graph 116, which each depict a history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates. More specifically, the graph 112, the graph 114, and the graph 116 illustrate the MCMC inversion of multi-frequency EM measurements of conductivity and permittivity (shown in FIG. 6.3) to estimate clay surface conductance λ_(c) (e.g., shown in graph 112), graphite contact angle θ (e.g., shown in graph 114), and water conductivity σ_(w) (e.g., shown in graph 116) for oil/water-filled porous material containing water-wet sand and clays and slightly oil-wet graphite.

FIGS. 11A, 11B, and 11C show a graph 118, a graph 120, and a graph 122, which each depict a histogram of MCMC inversion-derived estimates of clay surface conductance, graphite contact angle, and water conductivity. More specifically, the graph 118, the graph 120, and the graph 120 illustrate a histogram of MCMC inversion-derived estimates of clay surface conductance λ_(c) (e.g., shown in graph 118), graphite contact angle θ (e.g., shown in graph 120), and water conductivity σ_(w) (e.g., shown in graph 122). The line 102 represents the original values of the properties and the region between lines 104 and 106 represent 90% HPD interval of the inversion-derived estimates.

FIGS. 12A and 12B show a graph 124 of multi-frequency MS measurements and a graph 126 of model predictions based on inversion-derived estimates. More specifically, the graph 124 and graph 126 illustrate a comparison of the multi-frequency EM measurements against the mechanistic model predictions based on the inversion-derived estimates of effective conductance and effective permittivity.

FIGS. 13A and 13B show a graph 128 and a graph 130 that each history of Markov Chain Monte Carlo (MCMC) inversion-derived estimates. More specifically, the graph 128 and the graph 130 illustrate the MCMC inversion of multi-frequency EM measurements of conductivity and permittivity (shown in FIG. 7.3) to estimate graphite contact angle θ and oil saturation S_(o) for oil/water-filled porous material containing water-wet sand and clays and oil-wet graphite.

FIGS. 14A and 14B show a graph 132 and a graph 134 that each depict a third histogram of MCMC inversion-derived estimates of clay surface conductance, graphite contact angle, and water conductivity. More specifically, the graph 132 and the graph 134 illustrate the histogram of MCMC inversion-derived estimates of graphite contact angle θ and oil saturation S_(o). The line 102 represents the original values of the properties and the region between lines 104 and 106 represent 90% HPD interval of the inversion-derived estimates.

FIGS. 15A and 15B show a graph 136 of multi-frequency MS measurements and a graph 138 model predictions based on inversion-derived estimates. More specifically, the graph 136 and the graph 138 illustrate a comparison of the multi-frequency EM measurements against the mechanistic model predictions based on the inversion-derived estimates of effective conductance and effective permittivity.

Accordingly, the present disclosure is directed to techniques for quantitatively determining effects of wettability (e.g., contact angle) of conductive particles on the multi-frequency complex conductivity of fluid-filled porous materials, such as a geological formation. In some embodiments, the techniques include developing a material and subsurface characterization model 46. The material and subsurface characterization model 46 may be developed by solving the Young-Laplace equation as discussed herein. Additionally, the material and subsurface characterization model 46 may be developed by applying the Poisson-Nernst-Planck (PNP) equation to quantify dipolarizability of a partially wetted graphite particle. Further, developing the model may include using an effective medium model to combine the interfacial polarization effects of non-conductive particles (e.g., sand and clay) and conductive particles (e.g., graphite and pyrite) to compute the complex conductivity of fluid-filled porous material containing strongly water-wet non-conductive particles and conductive particles of any wettability.

NOMENCLATURE

-   -   PPIP model=perfectly polarized interfacial polarization model     -   SCAIP model=surface-conductance-assisted interfacial         polarization model     -   a=characteristic length of inclusion phase (m)     -   A_(o)=surface area of graphite particle covered by oil (m²)     -   A_(s)=surface area of graphite particle (m²)     -   A_(w)=surface area of graphite particle covered by water (m²)     -   B_(o)=Bond number     -   D_(j)=diffusion coefficient of charge carriers of medium j         (m²/s)     -   e=Euler's number     -   E₀=amplitude of the electric field (V)     -   ε₀=vacuum permittivity (8.854×10⁻¹² F/m)     -   ε_(eff)=effective dielectric permittivity of the mixture (F/m)     -   ε_(j)=dielectric permittivity of medium j (F/m)     -   ε_(r,j)=relative permittivity of medium j     -   f=frequency (Hz)     -   f_(i)(ω)=dipolarizability (dipolar field coefficient) of medium         j     -   ƒ(φ)=a function of wetting angle φ     -   g=gravitational acceleration (N/kg)     -   G=dimensionless form of h−h_(i)     -   h(r)=height of oil-water interface at any distance r away from         the vertical axis z (m)     -   ĥ=dimensionless form of h     -   h_(c)=height where the oil-water interface contacts the particle         surface (m)     -   h_(i)=height of oil-water interface in the absence of wetting of         graphite (far-field height) (m)     -   H=mean curvature of the meniscus surface (m⁻¹)     -   i=square root of −1     -   I₀=modified Bessel function of the first kind of order 0     -   K₀=modified Bessel function of the second kind of order 0     -   K₁=modified Bessel function of the second kind of order 1     -   L_(c)=capillary length (m)     -   λ=surface conductance (S)     -   ω=angular frequency of the electric field (rad/s)     -   Δp=Laplace pressure (Pa)     -   p_(o)=proportion of graphite surface that covered by oil (%)     -   p_(w)=proportion of graphite surface that covered by water (%)     -   φ=wetting angle (%)     -   ϕ=porosity of the porous media (%)     -   ϕ_(j)=volume fraction of medium j in the mixture (%)     -   ϕ_(o)=volume fraction of oil in the mixture (%)     -   ψ=angle between oil-water interface and the horizon (x-axis) at         contact point (°)     -   q=elementary charge (1.6×10⁻¹⁹ C)     -   r=distance from vertical axis z (m)     -   {circumflex over (r)}=dimensionless form of r     -   R=radius of graphite particle (m)     -   ρ_(o)=density of oil (kg/m³)     -   ρ_(w)=density of water (kg/m³)     -   S_(o)=oil saturation (%)     -   σ=interfacial tension between oil and water (N/m)     -   σ_(eff)=effective electrical conductivity of the mixture (S/m)     -   σ*_(eff)=effective complex electrical conductivity of the         mixture (S/m)     -   σ_(j)=electrical conductivity of medium j (S/m)     -   σ*_(j)=complex electrical conductivity of medium j (S/m)     -   θ=contact angle (°)

The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. 

1. A method for determining a wettability of one or more types of solid particles within a geological formation, the method comprising: receiving a plurality of electromagnetic (EM) measurements within a defined frequency range from an electromagnetic well-logging tool; and determining a contact angle associated with at least one type of solid particle within the geological formation based on the received plurality of EM measurements.
 2. The method of claim 1, wherein the contact angle is determined based on the received plurality of EM measurements using a frequency-dependent complex conductivity, a frequency-dependent complex permittivity, or both associated with the type of solid particle within the geological formation.
 3. The method of claim 1, comprising: providing as an input to a mechanistic model, one or more properties to be determined using the plurality of EM measurements and data indicative of a composition of the geological formation, wherein the one or more properties comprise the contact angle, and wherein the mechanistic model correlates one or more fluid phases, compositions, or both, to the contact angle of the at least one type of solid particle and correlates an interfacial polarization of the at least one type of solid particle to the contact angle of the at least one type of solid particle; and receiving, as an output generated from the mechanistic model, the frequency range.
 4. The method of claim 1, where the at least one type of solid particle comprises surface-charge bearing non-conductive particles.
 5. The method of claim 1, wherein the at least one type of solid particle comprises clay and graphite
 6. The method of claim 1, comprising determining an oil saturation associated with the geological formation comprising the at least one type of solid particle.
 7. An article of manufacturer comprising instructions that, when executed by at least one processor, cause the at least one processor to: receive one or more inputs indicative of properties of a geological formation as inputs to a mechanistic model, wherein the mechanistic model correlates one or more fluid phases, compositions, or both, to a contact angle of at least one type of solid particle associated with the geological formation and correlates an interfacial polarization of the at least one type of solid particles to the contact angle of the at least one type of solid particle; and generating, as an output by the mechanistic model, a set of frequencies to measure by a downhole tool, wherein the set of frequencies corresponds to where frequency dispersions in conductivity, permittivity, or both are measureable.
 8. The article of manufacture of claim 7, wherein the mechanistic model is developed based on solving a Young-Laplace equation to determine a spreading of oil and water phase around a conductive particle, invoking a Poisson-Nernst-Planck (PNP) equation to quantify dipolarizability of a partially wetted graphite particle, and using an effective medium model to combine the interfacial polarization effects of non-conductive particles and conductive particles.
 9. The article of manufacture of claim 7, comprising instructions that, when executed by the at least one processor, cause the at least one processor to: receive a plurality of electromagnetic (EM) measurements associated with a geological formation and acquired by an electromagnetic well-logging tool according to the generated set of frequencies; and determine a contact angle associated with at least one type of solid particle within the geological formation based on the received plurality of EM measurements.
 10. The article of manufacture of claim 9, comprising instructions that, when executed by the at least one processor, cause the at least one processor to: invert the plurality of EM measurements to generate one or more properties as an output, wherein the one or more properties comprise the contact angle.
 11. The article of manufacture of claim 10, comprising inverting using a Markov Chain Monte Carlo (MCMC) inversion.
 12. The article of manufacturer of claim 10, wherein the properties comprise both the contact angle and an oil saturation associated with the geological formation.
 13. The article of manufacture of claim 7, comprising instructions that, when executed by the at least one processor, cause the at least one processor to: receive an input indicative of a type of solid particle within the geological formation.
 14. The article of manufacture of claim 7, wherein the set of frequencies are a plurality of discrete frequencies.
 15. A system for determining physical properties of a porous, fluid-filled geological formation comprising: a data processing system, comprising: a processor; a memory storing instructions that, when executed by the processor, cause the processor to: receive, as an input to a mechanistic model, one or more inputs indicative of estimated properties of the porous, fluid-filled geological formation, wherein the mechanistic model correlates one or more fluid phases, compositions, or both, to a contact angle of at least one type of solid particle and correlates an interfacial polarization of the at least one type of solid particle to the contact angle of the ay least one type of solid particle; generate, as an output by the mechanistic model, a set of frequencies to measure by a downhole tool, wherein the set of frequencies corresponds to where frequency dispersions in conductivity, permittivity, or both are measureable; and the electromagnetic well-logging tool configured to tune an electromagnetic (EM) measurement based on the set of frequencies and acquire measurements based on the set of frequencies.
 16. The system of claim 15, wherein the input physical properties includes at least one of a conduct angle of conductive particles and a contact angle of surface-charge-beating particles.
 17. The system of claim 15, wherein a number of frequencies within the set of frequencies is at least three times a number of the input physical properties to be estimated.
 18. The system of claim 15, comprising instructions, stored within the memory, that, when executed by the processor, cause the processor to: receive the EM measurements acquired by the downhole tool; and determine a contact angle associated with at least one type of solid particles within the geological formation based on the received EM measurements.
 19. The system of claim 18, comprising instructions, stored within the memory, that, when executed by the processor, cause the processor to: determine both the contact angle and an oil saturation associated with the geological formation.
 20. The system of claim 15, wherein the set of frequencies are a plurality of discrete frequencies. 